Monitors have heretofore been adapted to be tilted about a horizontal axis to face the operator and have been mounted on supports that permit raising and lowering the display screen of the monitor relative to the line of sight of the operator and turning the monitor about a vertical axis to face the operator. One example of such a terminal is the one marketed by Wyse Technology. That terminal includes a monitor supported on one end of an arm pivotally connected at its opposite end to a base. Supports of this nature, however, physically move the monitor horizontally relative to the base as the supporting arm is moved between its raised (vertical) position and its lowered (horizontal) position, that is, when the monitor is raised and lowered, it also moves toward and away from the operator.
This makes it difficult to adjust the position of the monitor relative to the operator since, when the monitor is raised and lowered, it must also be adjusted forwardly, backwardly or sidewise to reposition it relative to the operator as it was before it was raised or lowered. At the same time, shifting the monitor horizontally relative to a base as it is raised and lowered also shifts its center of gravity, which in turn requires a larger and more massive base to support the monitor upright on the base--or in other words, to keep the monitor from becoming unbalanced and falling over.
In the Wyse terminal, the monitor is disposed on a base that provides for rotation of the monitor about a vertical axis as well as tilting about a horizontal axis, and the monitor and base are mounted as a unit on the supporting means for raising and lowering the monitor. This arrangement increases the weight of the elements that are elevated which in turn requires a more substantial supporting means and/or more effort to raise and lower the monitor.
Another problem with monitors such as those in the Wyse terminal is that the tilt angle of the display screen relative to the vertical is also moved as the monitor is raised and lowered. This requires that the tilt angle of the display screen be readjusted whenever the elevation of the monitor is adjusted. Using a parallelogram in the arm of course will maintain the tilt angle of the display screen as the monitor is raised and lowered but the monitor is still shifted horizontally relative to the supporting base.
With a terminal supported on an arm that is connected to the monitor through a ball and socket connection, the tilt angle of the display screen is limited to perhaps 20.degree.. While the total tilt angle can be divided between the positive and negative angles of tilt, only a limited fraction of this is normally available for the negative tilt angle.